JIRA Issues Macro should respect the case of custom JIRA Fields

Summary

When working with Custom Fields displayed the JIRA issues macro, Confluence will ignore the case of the fields as they're input into Confluence.

Steps to Reproduce

1. In JIRA, create a custom field, and call it "RN Summary"
2. In Confluence, create a page, and insert the JIRA Issues Macro
3. Under "Display Options" select "Table"
4. Under "Display Options" add the Custom Field to the "Columns to Display" section
5. Save the page, and view the table

Expected Result

The column header is shown matching the case in JIRA - in this case, "RN Summary"

Actual Result

The column header is displayed using capitalisation. Inspecting the header column reveals the following inline style applied to all of the header columns in the table:

style="text-align: left; text-transform: capitalize;"

Additionally, the text inside the header column is lower case.